For a long time, stand-by or emergency power has been used by the railroad industry to operate signal systems, switch systems and the like. These systems include the appropriate control equipment along with a bank of batteries that are usually stored in a shed or other small structure. These batteries are stationary as distinguished from batteries for example that are used in lift trucks. The battery remains stationary for its useful life, which may be seven years or more.
Historically, these batteries have been contained in trays which are fabricated from relatively heavy metal such as steel. Typically, five pieces comprising the bottom and the four sides welded at every juncture to form the box. The welding is traditionally along all of the seams or junctures and such welding is of course difficult to do precisely. Since the batteries themselves are heavy, it is necessary to have seams which do not come apart. Additionally, the batteries have from three to five psig internal pressure which must be contained over the life of the battery, particularly in the later years as pressure may increase. The batteries are sealed, maintenance free batteries using gelled electrolytes, connected either in series or in parallel.
In the conventional manner of manufacturing the trays for holding these batteries, it has been found that welding markedly changes the shape of the tray. It is desirable to have the trays uniformly fit a predetermined rectangular shape which is optimally suited for a particular size battery. Recent efforts to use rechargeable batteries have been made, using solar panels to generate a steady electrical charge which is regulated by appropriate control electronics. This raises additional concern for build up of pressure in the battery since these batteries are completely unattended and it is more than ever important that the trays holding the batteries will not fail.
As systems become more complicated and extensive, increasingly performing more functions, more power is required. Batteries are stacked on pallets in these remote unattended locations, sometimes with sixty or seventy batteries of the same size all hooked together. The stacks of batteries reach 10 to 12 feet in height. This load places severe stress loads on the battery tray or container, and failure has occurred along seam welds of those conventional tray devices described above. Failure of the tray may even result in crushed batteries and expensive repair, not to mention interruption in reliability of the backup emergency power supply system.
One additional difficulty with prior art tray devices is the need for significant amount of labor in the manufacture, not only for the long seam welding procedures but also for the extensive grinding that is required. The metal needs to be removed in order to permit the battery to fit within the predetermined rectangular space, and thus spurs and other irregularities are to be removed. When aesthetics require a smooth outer appearance grinding costs are even greater Since, the tray itself is often placed in specifically sized cavities in a larger system, rough edges, burrs, spurs and the like must be removed to enable a closer tolerance and fit, as well as to protect those who install and remove the trays from cuts and scratches. Further, typically these trays are finished with an sulfuric acid resistant paint which will only adhere effectively to smooth metallic surfaces. The welding technique utilized in the tray of the present invention obviates the need for grinding and other expensive operations to prepare the surface for the paint finish.
Recently, cable systems, telephone relay stations, and other communication industry components have begun using remote structures with reserve power in the same way the railroad industry has done. The tremendous expected growth of fibre optics systems will place an extremely large demand for such remote power systems. Various regional Bell operating companies which service local calls are developing more extensive units including what has been termed a universal enclosure for remote terminal sites. Space considerations and placement of the battery is more important now then ever before.
Accordingly, it is an object of the present invention to provide tray devices for long term storage of batteries.
Another object of the present invention is to provide a tray device which has more uniform conformity to a predetermined rectangular size or shape, when that predetermined size or shape is to be filled with another object, such as a battery.
Yet another object of the present invention is to provide a tray device which does not require a substantial amount of post welding grinding to remove rough edges, burrs, spurs and the like.
It is a specific object of the present invention to provide a tray device which maintains structural integrity while requiring the use of less material and less labor in its manufacture.
Yet another objection of the present invention is to provide a tray device which conforms to a rectangular shape and which eliminates some welding steps.
Other objects will appear here and after.